U.S. patent application number 12/695414 was filed with the patent office on 2010-08-12 for manufacturing method of tiles.
This patent application is currently assigned to Tagawasangyo Co., Ltd.. Invention is credited to Katsuyuki Nakano, Tetsuro Oike, Nobuyoshi YUKIHIRA.
Application Number | 20100201022 12/695414 |
Document ID | / |
Family ID | 42543244 |
Filed Date | 2010-08-12 |
United States Patent
Application |
20100201022 |
Kind Code |
A1 |
YUKIHIRA; Nobuyoshi ; et
al. |
August 12, 2010 |
MANUFACTURING METHOD OF TILES
Abstract
A manufacturing method of tiles includes the steps of: preparing
mixed powder having a water content of 2 to 7% by mixing 30 to 80
parts by weight of calcium hydroxide powder or dolomite plaster
powder, 20 to 70 parts by weight of porous aggregate, 0.1 to 5
parts by weight of a first photocatalyst and water; filling the
mixed powder into a mold of a molding machine; forming a formed
body by pressurizing the filled mixed powder; curing the formed
body in a carbon dioxide atmosphere; and forming a thin layer made
of a second photocatalyst on a surface of the formed body.
Inventors: |
YUKIHIRA; Nobuyoshi;
(Tagawa-shi, JP) ; Oike; Tetsuro; (Tagawa-shi,
JP) ; Nakano; Katsuyuki; (Fukuoka-shi, JP) |
Correspondence
Address: |
JORDAN AND HAMBURG LLP
122 EAST 42ND STREET, SUITE 4000
NEW YORK
NY
10168
US
|
Assignee: |
Tagawasangyo Co., Ltd.
Tagawa-shi
JP
|
Family ID: |
42543244 |
Appl. No.: |
12/695414 |
Filed: |
January 28, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10565035 |
Mar 29, 2006 |
|
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PCT/JP2004/010054 |
Jul 14, 2004 |
|
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12695414 |
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Current U.S.
Class: |
264/113 |
Current CPC
Class: |
C04B 41/5041 20130101;
C04B 41/5041 20130101; E04F 13/148 20130101; C04B 28/10 20130101;
C04B 28/10 20130101; C04B 41/5041 20130101; C04B 20/002 20130101;
C04B 40/0231 20130101; C04B 41/4537 20130101; C04B 2111/00827
20130101; C04B 14/305 20130101; C04B 40/0259 20130101; B01J 35/004
20130101; C04B 41/009 20130101; C04B 28/10 20130101; C04B 41/65
20130101; B28B 3/02 20130101; C04B 41/009 20130101; C04B 2111/00594
20130101 |
Class at
Publication: |
264/113 |
International
Class: |
B27N 3/02 20060101
B27N003/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 15, 2003 |
JP |
2003-274883 |
Claims
1. A manufacturing method of tiles comprising the steps of:
preparing mixed powder having a water content of 2 to 7% by mixing
30 to 80 parts by weight of calcium hydroxide powder, 20 to 70
parts by weight of porous aggregate, 0.1 to 5 parts by weight of a
first photocatalyst and water; filling the mixed powder into a mold
of a molding machine; forming a formed body by pressurizing the
filled mixed powder at a forming pressure of 15 to 80 MPa; curing
the formed body by holding the formed body formed by the step for
forming the formed body in a carbon dioxide atmosphere containing 3
to 30% of carbon dioxide for 8 hours or more; and forming a thin
layer made of a second photocatalyst on a surface of the formed
body by spraying a solution in which a second photocatalyst is
dispersed to the surface of the formed body cured by the step for
curing the formed body.
2. A manufacturing method of tiles according to claim 1, wherein
the first photocatalyst is a composite of an absorption carrier and
a metal compound having a photocatalytic action.
3. A manufacturing method of tiles according to claim 2, wherein
the step of forming the formed body is performed in an atmosphere
where a pressure is reduced to -80 to -100 kPa.
4. A manufacturing method of tiles according to claim 3, wherein
the solution in which the second photocatalyst is dispersed is
prepared by mixing alcohol, titanium tetra alkoxide, and an amount
of water exceeding an amount of said titanium tetra alkoxide,
separating anatase titania fine particles and amorphous titania
fine particles formed in a mixed liquid from a solvent, drying the
anatase titania fine particles and the amorphous titania fine
particles, and dispersing the dried fine particles into acid
solution.
5. A manufacturing method of tiles comprising the steps of:
preparing mixed powder having a water content of 2 to 7% by mixing
30 to 80 parts by weight of dolomite plaster powder, 20 to 70 parts
by weight of porous aggregate, 0.1 to 5 parts by weight of a first
photocatalyst and water; filling the mixed powder into a mold of a
molding machine; forming a formed body by pressurizing the filled
mixed powder at a forming pressure of 15 to 80 MPa; curing the
formed body by holding the formed body formed by the step for
forming the formed body in a carbon dioxide atmosphere containing 3
to 30% of carbon dioxide for 8 hours or more; and forming a thin
layer made of a second photocatalyst on a surface of the formed
body by spraying a solution in which a second photocatalyst is
dispersed to the surface of the formed body cured by the step for
curing the formed body.
6. A manufacturing method of tiles according to claim 5, wherein
the first photocatalyst is a composite of an absorption carrier and
a metal compound having a photocatalytic action.
7. A manufacturing method of tiles according to claim 6, wherein
the step of forming the formed body is performed in an atmosphere
where a pressure is reduced to -80 to -100 kPa.
8. A manufacturing method of tiles according to claim 7, wherein
the solution in which the second photocatalyst is dispersed is
prepared by mixing alcohol, titanium tetra alkoxide, and an amount
of water exceeding an amount of said titanium tetra alkoxide,
separating anatase titania fine particles and amorphous titania
fine particles formed in a mixed liquid from a solvent, drying the
anatase titania fine particles and the amorphous titania fine
particles, and dispersing the dried fine particles into acid
solution.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a Continuation-in-Part of U.S.
application Ser. No. 10/565,035 filed on Mar. 29, 2006, which is
the national phase of International Application PCT/JP2004/010054
filed on Jul. 14, 2004, which claims the benefits of Japanese
Patent Application No. 2003-274883 filed on Jul. 15, 2003, the
entire contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a manufacturing method of
tiles which is formed in a tile shape using calcium hydroxide
powder or dolomite plaster powder as a raw material.
[0004] 2. Description of the Related Art
[0005] Conventionally, a mortar which is formed into a paste shape
by adding and mixing water into calcium hydroxide powder or
dolomite plaster powder has been popularly used as a construction
material since the mortar exhibits excellent properties such as
respiratory property, water resistant property and weatherability
when the mortar is applied to a wall or the like and is dried.
[0006] On the other hand, in recent years, the air pollution caused
by volatile harmful substances such as formaldehyde and formalin
has become a social problem.
[0007] Accordingly, lately, there has been developed a wall
material in which a photocatalyst having a function of decomposing
harmful substances with the irradiation of ultraviolet rays is
added to the mortar (for example, see Japanese Patent Laid-open
Publication Heill (1999)-264224).
SUMMARY OF THE INVENTION
[0008] However, although the above-mentioned conventional wall
material in which the photocatalyst is added to the mortar can
decompose the harmful substances due to an action of the
photocatalyst and can obtain an advantageous effect that the air
pollution can be prevented, in actually applying the mortar to a
wall surface, skilled workers are required and, at the same time,
the installation requires a considerable labor and time and hence,
there exists a possibility that a construction cost is sharply
pushed up.
[0009] Inventors of the present invention have made extensive
studies and have found that a tile-shaped formed article (molded
article) can be manufactured by pressure-forming (press-forming) a
mortar to which a photocatalyst is added, and it is possible to
reduce labor, time and cost required for installation by using the
tile manufactured in such a manner as a wall material.
[0010] Further, the inventors of the present invention also have
found that although the mere pressure-forming of the mortar to
which the photocatalyst is added into a tile shape may overcome a
drawback on the installation, the ability to decompose the harmful
substances with a photocatalyst is lowered.
[0011] Upon investigating a cause which brings about the reduction
of the ability of the photocatalyst to decompose the harmful
substance by pressure-forming the mortar to which the photocatalyst
is added, the inventors of the present invention have found that
when the mortar to which the photocatalyst is added is subjected to
pressure-forming at a relatively high pressure, a surface of the
mortar is made smooth and hence, the permeability which the mortar
originally possesses is impaired.
[0012] Accordingly, it is an object of the present invention to
provide a manufacturing method of tiles which can enjoy
advantageous effects acquired by a photocatalyst and can enhance
workability without impairing the permeability which a mortar
possesses.
[0013] According to one aspect of the present invention, there is
provided a manufacturing method of tiles including the steps of:
preparing mixed powder having a water content of 2 to 7% by mixing
30 to 80 parts by weight of calcium hydroxide powder, 20 to 70
parts by weight of porous aggregate, 0.1 to 5 parts by weight of a
first photocatalyst and water; filling the mixed powder into a mold
of a molding machine; forming a formed body by pressurizing the
filled mixed powder at a forming pressure of 15 to 80 MPa; curing
the formed body by holding the formed body formed by the step for
forming the formed body in a carbon dioxide atmosphere containing 3
to 30% of carbon dioxide for 8 hours or more; and forming a thin
layer made of a second photocatalyst on the surface of the formed
body by spraying a solution in which a second photocatalyst is
dispersed to the surface of the formed body cured by the step for
curing the formed body. In the above-mentioned step of preparing
the mixed powder, 30 to 80 parts by weight of calcium hydroxide
powder may be replaced with 30 to 80 parts by weight of dolomite
plaster powder.
[0014] In the above-mentioned manufacturing method of tiles, the
first photocatalyst may preferably be a composite of an absorption
carrier and a metal compound having a photocatalytic action.
[0015] In the above-mentioned manufacturing method of tiles, the
step of forming the formed body may be performed in an atmosphere
where a pressure is reduced to -80 to -100 kPa.
[0016] In the above-mentioned manufacturing method of tiles, the
solution in which the second photocatalyst is dispersed may be
prepared by mixing alcohol, titanium tetra alkoxide, and an amount
of water exceeding an amount of titanium tetra alkoxide, separating
anatase titania fine particles and amorphous titania fine particles
formed in a mixed liquid from a solvent, drying the anatase titania
fine particles and the amorphous titania fine particles, and
dispersing the dried fine particles into acid solution.
[0017] The present invention can acquire the following advantageous
effects.
[0018] That is, the present invention provides the manufacturing
method of tiles including the steps of: preparing mixed powder
having a water content of 2 to 7% by mixing 30 to 80 parts by
weight of calcium hydroxide powder or dolomite plaster powder, 20
to 70 parts by weight of porous aggregate, 0.1 to 5 parts by weight
of first photocatalyst and water; filling the mixed powder into a
mold of a molding machine; forming a formed body by pressurizing
the filled mixed powder at a forming pressure of 15 to 80 MPa;
curing the formed body by holding the formed body formed by the
step for forming the formed body in a carbon dioxide atmosphere
containing 3 to 30% of carbon dioxide for 8 hours or more; and
forming a thin layer made of a second photocatalyst on a surface of
the formed body by spraying a solution in which the second
photocatalyst is dispersed to the surface of the formed body cured
by the step for curing the formed body. Due to such an operation,
the tile can be manufactured by pressure-forming at a pressure
which allows the formation of open pores (open pores) in a surface
of the tile. Accordingly, it is possible to provide a manufacturing
method of tiles which can enjoy advantageous effects acquired by a
photocatalyst and can enhance workability without impairing the
permeability which a tile material possesses. Further, it is
possible to reduce labor, time and cost required for installation
without decreasing the ability of decomposing harmful substances
using the photocatalyst.
[0019] Particularly, by applying the photocatalyst to the surface
of the tile, it is possible to enhance the ability of decomposing
the harmful substances.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is an explanatory view showing a vacuum molding
machine;
[0021] FIG. 2 is a graph showing a result of a formaldehyde
decomposing test (mortar);
[0022] FIG. 3 is a graph showing a result of a formaldehyde
decomposing test (tiles);
[0023] FIG. 4 is a schematic view showing the vicinity of a surface
of a cross section of a tile (a specimen B) in an enlarged
manner;
[0024] FIG. 5 is a schematic view showing the vicinity of a surface
of a cross section of a tile (a specimen C) in an enlarged manner;
and
[0025] FIG. 6 is a schematic view showing the vicinity of a surface
of a cross section of a tile (a specimen D) in an enlarged
manner.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0026] Hereinafter, a manufacturing method of tiles according to
this embodiment is explained. The manufacturing method of tiles
according to this embodiment is characterized by pressure-forming
raw material powder to which a photocatalyst is added into a tile
shape. One of the characteristics of the tile manufactured by the
manufacturing method of tiles according to this embodiment is that
the tile has a favorable moisture adjusting function. To be more
specific, corresponding to a change of moisture in an atmosphere
around the tile, the tile diffuses moisture held therein or absorbs
moisture in air. By arranging such a tile indoors, it is possible
to adjust moisture in indoor air.
[0027] Further, the tile manufactured by the manufacturing method
of tiles according to this embodiment, when the tile absorbs
moisture in air, can also efficiently absorb odor substances,
chemical substances, allergen and the like in air. In the
explanation made hereinafter, odor substances, chemical substances,
allergen and the like in air are collectively referred to as
foreign substances. The tile which absorbs the foreign substances
generates a photocatalytic action when light is radiated to the
tile, and decomposes the foreign substances thus making the foreign
substances harmless. Making the foreign substances harmless implies
making the odor substances odorless, making the harmful chemical
substances harmless or deactivating a function of allergen.
Decomposed harmless products are discharged from the tile along
with the diffusion of moisture. After discharging the decomposed
products, the tile can absorb other harmful substances and can
decompose the harmful substances again. By arranging such a tile
indoors, it is possible to purify indoor air.
[0028] These advantageous effects are derived from the
characteristic surface structure which the tile manufactured by the
manufacturing method of tiles according to this embodiment
possesses. The surface structure is explained in detail later using
drawings.
[0029] Further, such characteristic surface structure is formed by
the manufacturing method of tiles which characterizes this
embodiment. This characteristic manufacturing method includes, to
be more specific, a power preparation step in which mixed powder in
which plural kinds of powder raw material are mixed is prepared, a
powder filling step in which the mixed power is filled in a mold of
a molding machine, a pressure forming step in which a formed body
is formed by pressurizing the filled mixed powder, a curing step in
which the formed body is formed by the pressure forming step is
held in a carbon dioxide atmosphere having higher carbon dioxide
concentration compared to atmospheric air, and a photocatalytic
thin-layer forming step in which a thin layer made of a
photocatalytic body is formed on a surface of the formed body which
is cured in the curing step. Hereinafter, the manufacturing method
of tiles according to this embodiment is explained more
specifically in order of these steps.
[0030] First of all, the mixed powder preparation step is
explained. The mixed powder contains 30% or more of slaked lime
(calcium hydroxide). The mixed power also contains an inorganic
material, fiber for plastering and glue at proper ratios.
[0031] As the raw material which is used in the mixed powder
preparation step, for example, calcium hydroxide powder, an
inorganic material, a porous aggregate, fiber, glue, water and the
like can be named. Here, all of these raw materials are not always
necessary for preparing the mixed powder. That is, the mixed powder
can be prepared without using fiber for plastering or glue, for
example.
[0032] As calcium hydroxide powder, calcium hydroxide powder
manufactured for industrial use in general may be used. A particle
size of calcium hydroxide powder may preferably be approximately
300 meshes. To be more specific, calcium hydroxide powder may
preferably have the particle size distribution where a size peak of
the particles falls within a range from 1 to 10 .mu.m and a size of
the particles on a large-particle-size side or a tail side is
approximately 75 .mu.m. Further, dolomite plaster powder can be
used in place of calcium hydroxide powder in the same manner as
described above. Here, dolomite plaster is a material obtained by
baking dolomite at a temperature of 950 to 1100.degree. C., by
subjecting baked dolomite to hydration reaction and by adjusting a
particle size of hydrated dolomite. Here, although the explanation
is made with respect to the tile which is manufactured using
calcium hydroxide powder, the tile which uses dolomite plaster
powder in place of calcium hydroxide can be manufactured by the
same manufacturing method and hence, the manufacturing method of
the tile using dolomite plaster powder is omitted.
[0033] As the inorganic material, for example, a photocatalyst body
which exhibits a photocatalytic ability, a pigment for coloring and
the like can be named. The photocatalyst body used as a raw
material functions as a first photocatalyst body. As the first
photocatalyst body, for example, metal compound powder having a
photocatalytic ability can be used. However, to enjoy the
photocatalytic ability of the first photocatalyst body, it is
desirable to use a composite of an absorption carrier having the
gel structure and a metal compound having a photocatalytic ability.
The absorption carrier is not particularly limited provided that
the absorption carrier is a carrier which exhibits an absorption
force for odor substances or the like in moisture or air. As the
composite suitably used as the first photocatalyst body, for
example, it is possible to use "Seventol N-PC90" produced by Takeda
Pharmaceutical Company Limited. As a metal compound which possess
photocatalytic ability, a metal compound having various crystal
structure such as an oxide semiconductor such as titanium oxide or
zinc oxide or a semiconductor sulfide such as titanium oxide or
zinc oxide. As a photocatalyst, to be more specific, for example,
TiO.sub.2, ZnO, SrTiO.sub.3, BaTiO.sub.3, BaTiO.sub.4,
BaTi.sub.4O.sub.9, K.sub.2NbO.sub.3, Nb.sub.2O.sub.5,
Fe.sub.2O.sub.3, Ta.sub.2O.sub.5, K.sub.3Ta.sub.3Si.sub.2O.sub.3,
WO.sub.3, SnO.sub.2, Bi.sub.2O.sub.3, BiVO.sub.4, NiO, Cu.sub.2O,
RuO.sub.2, CeO.sub.2 and the like can be named. Among these
photocatalysts, the use of TiO.sub.2 is preferable because
TiO.sub.2 is harmless and is available at a relatively low cost.
Further, provided that the metal compound which exhibits a
photocatalytic ability with a visible light, even indoors, the
metal compound can exhibit a photocatalytic ability by receiving
light such as indoor illumination or the like. As the pigment for
coloring, a known product can be used.
[0034] As the further inorganic material, calcium carbonate, barium
carbonate, barium hydroxide or the like may be used. As the fiber,
Manila hemp, Japanese paper, hemp palm, wooden pulp, synthetic
fiber, glass fiber, or the like may be used. As the glue, a natural
glue such as glue, nonglutinous rice, konyak powder, glue plant, or
the like, a synthetic glue such as polyvinyl alcohol, methyl
cellulose, hydroxyl ethyl cellulose, hydroxyl propyl cellulose or
the like may be used.
[0035] As a porous aggregate used in the power preparation step,
for example, shirasu, sepiolite, zeolite, coal ash, diatomaceous
earth, sludge incinerated earth or a mixture of a plurality of
these materials can be used. In the same manner as calcium
hydroxide powder, the porous aggregate contributes to the
absorption and the diffusion of moisture and foreign substances. It
is preferable to set the particle size of the porous aggregate to
approximately 50 to 300 .mu.m. This porous aggregate performs a
favorable function as an aggregate.
[0036] Further, an inorganic binder which has the property to be
cured by reacting with a carbonic acid gas or moisture in the air
may be added to the mixed powder when necessary. Here, as the
inorganic binder, a material such as the slaked lime, a dolomite, a
gypsum, a magnesium hydroxide, a cement, or the like which easily
reacts with carbonic acid gas or water in air to form a cured body
is used. One material out of a group of slaked lime, dolomite,
gypsum, magnesium hydroxide, cement, and the like may be singularly
used for the inorganic binder. Alternatively, a mixture of two or
more kind of these materials may be used. Further, water may be
added to and mixed with the mortar until the mortar obtains given
moisture content.
[0037] Then, in the powder preparation step, mixed powder having a
water content of 2 to 10% is prepared by mixing 30 to 80 parts by
weight, preferably 40 to 70 parts by weight of calcium hydroxide
powder, 20 to 70 parts by weight, preferably 30 to 60 parts by
weight of porous aggregate, 0.1 to 5 parts by weight of first
photocatalyst body and water. When the water content is below 2%,
the moldability is deteriorated. To be more specific, in the
pressure forming step described later, even when a forming pressure
of 15 to 80 MPa is applied to mixed powder, a binding force is low
so that a formed body becomes extremely fragile. On the other hand,
when the water content exceeds 10%, with the application of a
forming pressure of 15 to 80 MPa to the mixed powder, moisture
exudes from a formed body thus adversely influencing workability.
Further, the presence of surplus moisture obstructs the absorption
of carbon dioxide in the curing step described later thus bringing
about the prolongation of manufacturing time and the deterioration
of strength of a tile. By setting the water content to 2 to 10%,
preferably to 2 to 7%, it is possible to manufacture a tile having
a sufficient strength within a time as short as possible while
maintaining favorable moldability and operability.
[0038] Next, the power filling step is explained. In the powder
filling step, the mixed powder is filled in a mold of a molding
machine for molding a tile.
[0039] Next, the pressure forming step is explained. In the
pressure forming step, a formed body is formed by pressurizing the
mixed powder using the molding machine. Here, the pressure used in
the pressure forming step is set to a relatively low pressure which
is sufficient to form open pores on a surface of the formed body
after pressure forming. This pressure forming step is explained
later in conjunction with the drawings.
[0040] Next, the curing step is explained. In the curing step, the
formed body formed in the pressure forming step is held in a carbon
dioxide atmosphere containing 3 to 35%, preferably 20 to 30% of
carbon dioxide for 8 hours or more. In this curing step, calcium
hydroxide powder which constitutes the formed body is gradually
carbonated and powder particles are bonded to each other thus
enhancing strength of the formed body. Accordingly, it is possible
to enhance the handling property of the tile obtained by curing.
Here, in this curing step, when the concentration of carbon dioxide
is below 3%, the progress of carbonization of calcium hydroxide
powder becomes slow and hence, a time necessary for this step is
prolonged and hence, this concentration is not desirable. Further,
also when the concentration of carbon dioxide exceeds 35%, it is
difficult to expect the shortening of time necessary for the curing
step. By setting the concentration of carbon dioxide to 3 to 35%,
preferably 20 to 30%, it is possible to perform the curing step
sufficiently within a short time.
[0041] Next, the photocatalyst-thin-film-layer forming step for
forming a thin layer made of a second photocatalyst on a surface of
the formed body by applying the second catalyst on the surface of
the formed body is performed. To be more specific, the formation of
the thin layer is performed by spraying a solution in which the
second photocatalyst is dispersed onto the surface of the formed
body. The spraying of the solution may be applied to the whole or a
part of the formed body. In general, one surface of the
plate-shaped tile is adhered to a wall or a floor and the other
surface of the tile is exposed to a space. Accordingly, it is
desirable to apply the solution to at least an exposed surface of
the formed body. The second photocatalyst is prepared by mixing
alcohol, titanium tetra alkoxide, and an amount of water exceeding
an amount of titanium tetra alkoxide, by separating anatase titania
fine particles and amorphous titania fine particles which are
formed in a mixed liquid from a solvent, and drying the anatase
titania fine particles and the amorphous titania fine particles.
The solution is prepared by dispersing the second photocatalyst
into an acid solution. For example, hydrogen peroxide water is used
as the acid solution.
[0042] To explain this solution more specifically, firstly,
titanium tetra alkoxide, for example, titanium tetra isopropoxyde
(TIP), alcohol such as isopropanol (IPA), water are mixed and
agitated at a predetermined moll ratio, for example,
TIP/IPA/water=1/5-10/10-80. Here, an amount of water is set larger
than an amount of TIP. For example, a mol ratio TIP/water between
TIP and water is set to 1/10-1/80, and preferably to 1/10-1/15.
Next, when the hydrolysis of TIP is accelerated by sufficiently
agitating the mixed liquid while controlling a temperature of the
mixed liquid to a predetermined temperature, for example,
25.degree. C., fine particles of anatase titania which is made of
crystalline titania and fine particles of amorphous titania which
is made of amorphous titania are formed in the mixed liquid. Here,
the mixing order may be set such that TIP and IPA are mixed to each
other firstly, and IPA and water are mixed into the mixed liquid
next such that the predetermined moll ratio is obtained.
[0043] Subsequently, the fine particles of anatase titania and the
fine particles of amorphous titania are separated from the solvent
using a filter, for example, and are dried by air ventilation at a
temperature of a predetermined temperature, for example,
100.degree. C. for 20 hours thus acquiring anatase titania powder
and amorphous titania powder (fine particle groups). These powders
form the second photocatalyst. Then, an acid solution such as a
hydrogen peroxide solution, for example, a solution containing 10
to 50 weight % of hydrogen peroxide (hydrogen peroxide water) is
added to the second photocatalyst. The solution (titania solution)
is agitated while controlling a temperature at 20.degree. C. or
less, preferably at 5 to 20.degree. C., for example so as to
dissolve titania powder into the solution and, at the same time, to
disperse titania in the solution. Due to such an operation, a
solution which is a titania dispersion liquid in which the second
photocatalyst is dispersed is obtained. Even when the mixing mol
ratio of water with respect to TIP and IPA exceeds the
above-mentioned ratio, a formation reaction of anatase-titania is
not influenced by the excessive mol ratio. However, filtering of
such a mixed solution takes a long time and hence, it is preferable
to set TIP/IPA/water to 1/5/10 to 80, preferably to 1/5/10-15.
[0044] The solution prepared in this manner is sprayed to a surface
of the formed body. Due to such spraying of the solution, a thin
film layer made of a photocatalyst body is formed on the surface of
the formed body along with the evaporation of moisture. It is
preferable to set a film thickness of the thin layer to
approximately 50 to 200 nm. When the film thickness is below 50 nm,
advantageous effects attributed to the photocatalyst are not
sufficiently acquired. On the other hand, when the film thickness
exceeds 200 nm, permeability through the open pores is impaired and
hence, the film thickness which exceeds 200 nm is not desirable. By
setting the film thickness to 50 to 200 nm, preferably 80 to 120
nm, the tile can ensure permeability while generating a
photocatalytic effect. The formation of the thin layer of the
photocatalytic body using the solution does not require baking.
Accordingly, there is no possibility that properties that materials
such as an inorganic porous material, clay and the like possess, to
be more specific, the absorption and diffusion ability of moisture
and foreign substances are deteriorated due to heating.
Accordingly, it is possible to manufacture the tile which can
sufficiently enjoy advantageous effects acquired by the
photocatalyst without impairing permeability that the tile
possesses. Further, the heat treatment is not applied to the tile,
there is no possibility that the change of color of the tile does
not occur during baking. Accordingly, a manufacturer can
manufacture the tile reproduces color and design that a
manufacturer intends to create without worrying about discoloration
after heating.
[0045] The manufacturing method of tiles according to this
embodiment adopts the above-mentioned steps and hence, it is
possible to reduce labor, time and cost necessary for
installation.
[0046] Further, the forming pressure at the time of
pressure-forming is set to the pressure which allows the formation
of open pores on the surface thereof and hence, a surface of the
formed body is made smooth whereby it is possible to preliminary
prevent the permeability from being impaired thus producing a
formed body having the permeability. Accordingly, it is possible to
prevent the reduction of the decomposing ability of foreign
substances using the photocatalyst.
[0047] Particularly, the photocatalyst is applied to the surface of
the formed body and hence, it is possible to enhance the ability of
decomposing foreign substances.
[0048] Further, the manufacturing method requires no heat treatment
such as baking, autoclaving or the like. Accordingly, there is no
possibility that the environment is polluted with a flue gas
generated by the heat treatment. The environmental pollution can be
prevented. Further, since the heat treatment is not performed, the
treatment cost can be reduced.
[0049] Further, various types of formed bodies may be molded
depending on shapes of a mold which is used at the time of forming
thus manufacturing formed bodies in a broad field.
[0050] Further, when the mixed powder is prepared by adding the
inorganic binder having the property to be cured by reacting with a
carbonic acid gas and the moisture in air, the surface of the
formed body can be cut, ground and polished easily before natural
curing. Further, even when the surface of the formed body is cut,
ground or polished, the surface of the formed body is naturally
cured in air thus ensuring the strength of the surface of the
formed body.
[0051] Next, the pressure-forming step is explained in further
detail in conjunction with the drawing. In the pressure-forming, a
vacuum molding machine shown in FIG. 1 is used. In the drawing, the
vacuum molding machine 20 is configured as follows. A lower mold 22
is arranged on a lower portion of a frame 21. A hydraulic elevating
cylinder 23 is arranged on an upper portion of the frame 21 in a
state that a distal end of a cylinder rod 24 extends downwardly. An
upper mold 25 is connected to the distal end portion of the
cylinder rod 24. Upon actuation of the elevating cylinder 23, the
upper mold 25 is elevated toward or lowered away from a recessed
portion 26 of the lower mold 22. In the drawing, numeral 27
indicates a vacuum pump 27 which is communicably connected with the
recessed portion 26 of the lower mold 22, numeral 28 indicates a
hydraulic pump, and numeral 29 indicates a hydraulic control
panel.
[0052] In the powder filling step, the above-mentioned mixed powder
is filled into the recessed portion 26 of the lower mold 22.
[0053] Next, upon the actuation of the vacuum pump 27, a
pressurizing space which is defined by the recessed portion 26 of
the lower mold 22 and the upper mold 25 is brought into an
approximately vacuum state of -80 KPa to -100 KPa, and the raw
material is formed into a plate shape or a block shape by pressure
forming using the forming machine 20. Here, it is preferable to
bring the pressurizing space into an approximately vacuum state of
-94 KPa to -100 KPa. When the pressure in the pressurizing space is
higher than -80 KPa, there may be a case that a size of capillary
holes 36 described later becomes large thus adversely influencing
the absorption and the diffusion of moisture and hence, the
pressure higher than -80 KPa is not desirable. On the other hand,
when the pressure in the pressurizing space is lower than -100 KPa,
there exists a possibility that the number of closed capillary
holes 36 is increased thus adversely influencing the absorption and
the diffusion of moisture and hence, the pressure lower than -100
KPa is not desirable.
[0054] Here, a forming pressure which is applied to the raw
material at the time of pressure-forming is set to 15 MPa to 80
MPa. This is because that when the forming pressure is 15 MPa or
less, a strength of the formed body is lowered, while when the
forming pressure is 80 MPa or more, as described later, the surface
of the formed body is made smooth and hence, the permeability is
impaired. This forming pressure differs depending on the raw
material to be formed and may be a pressure which allows the
formation of open pores in a surface of the formed body after
forming. Thus, the forming pressure is not limited to the pressure
range described above.
[0055] In this manner, by performing the pressure forming step in
an atmosphere where a pressure is reduced to -80 to -100 kPa,
substantially no air remains in the inside of the formed body thus
capable of forming a formed body having a high physical strength
and a favorable dimensional accuracy. To explain this step further,
by pressure-forming the mixed powder at a pressure of 15 MPa to 80
MPa in a reduced-pressure atmosphere of -80 to -100 kPa, it is
possible to form the open pores 34 having the main holes 35 and the
capillary holes 36 described later and hence, it is possible to
manufacture the tile which can enjoy advantageous effects
attributed to a photocatalyst without impairing permeability and
can improve installation property.
[0056] Further, when the formed body is cured by leaving the formed
body in air or in the carbon dioxide gas atmosphere after
pressure-forming, slaked lime or the like which is contained in the
formed body absorbs the carbonic acid gas and forms carbonic
calcium as indicated by a following reaction and hence, it is
possible to further increase the physical strength of the formed
body.
Ca(OH).sub.2+CO.sub.2=CaCO.sub.3+H.sub.2O
[0057] Further, different from the brick, tile or the like, the
heat treatment such as baking, autoclaving or the like is not
applied to the formed body. Accordingly, even when an inorganic
porous material, clay, a functional inorganic catalyst, an
antimicrobial and antifungal agent are applied to the mixed body,
there exists no possibility that these inorganic porous material,
clay and the like is influenced by heat and hence, it is possible
to form the formed body which holds characteristics which the
respective materials such as the inorganic porous materials, clay
and the like posses.
[0058] Further, since the heat treatment is not applied to the
formed body, the discoloration attributed to an unexpected change
in a kiln is not generated and hence, formed bodys having the color
equal to the mixed body before pressure-forming can be produced on
a mass production basis with sufficient reproducibility.
[0059] Further, different from cement products, the raw material is
not prepared in a slurry state and hence, efflorescence is not
generated whereby it is possible to allow the formed body to
sufficiently develop color by merely mixing 5 parts by weight or
less of pigment in the mixed body.
[0060] Further, it is possible to reinforce the bending strength of
the formed article by mixing fibers in the formed body.
[Examination of Photocatalytic Function]
[0061] Hereinafter, a decomposition effect of formaldehyde is
explained in conjunction with FIG. 2 and FIG. 3.
[0062] Here, a decomposition test is performed such that the
formaldehyde having the concentration of 1000 ppb is continuously
supplied to a room in which mortar or tiles is applied to an inner
wall surface, and when a given time elapses after starting the
supply of formaldehyde, ultraviolet rays are irradiated to the
inner wall surface, wherein the concentration of the formaldehyde
is time-sequentially measured while setting a point of time that
the irradiation of light is started as the reference (0
minute).
[0063] FIG. 2 shows a result of a test when the mortar in a paste
shape is applied to the wall surface and is dried.
[0064] In FIG. 2, a specimen 1 is obtained by applying only the
mortar, a specimen 2 is obtained by applying the mortar in which
the photocatalyst is added, a specimen 3 is obtained by applying
the mortar in which the photocatalyst is added and, thereafter,
making a surface of the mortar into a rough surface using a wooden
trowel, and a specimen 4 is obtained by coating the mortar in which
the photocatalyst is added and, thereafter, by further applying the
photocatalyst to a surface of the mortar.
[0065] As can be understood from FIG. 2, in all specimens 1 to 4,
formaldehyde is absorbed in the mortar within a short time after
the supply of formaldehyde and hence, the concentration of the
formaldehyde is decreased.
[0066] However, an absorption strength of the mortar is gradually
decreased along with a laps of time and hence, the concentration of
the formaldehyde is gradually increased.
[0067] Then, as a matter of course, due to the irradiation of
light, in the specimens 2 to 4 which contain the photocatalyst,
formaldehyde is decomposed by the photocatalyst and hence, the
concentration of formaldehyde is decreased.
[0068] Particularly, with respect to the specimen 4, it is possible
to remarkably decrease the concentration of formaldehyde to 20 ppb
or less.
[0069] On the other hand, FIG. 3 shows a result of a test when the
tiles are applied to a wall surface.
[0070] In FIG. 3, a specimen A is a tile which is obtained by
pressure-forming using mixed powder to which the first
photocatalytic body is not added as a raw material, a specimen B is
a tile obtained by pressure-forming at a forming pressure of 100
MPa using mixed powder to which the first photocatalyst is added as
a raw material, a specimen C is a tile obtained by pressure-forming
at a forming pressure of 30 MPa using mixed powder to which the
first photocatalyst is added as a raw material, and a specimen D is
a tile obtained by pressure-forming at a forming pressure of 30 MPa
using mixed powder to which the first photocatalyst is added as a
raw material and, thereafter, by further applying the second
photocatalyst to a surface of the tile. These tiles are applied to
a wall surface.
[0071] As can be understood from FIG. 3, in all specimens A to D,
formaldehyde is absorbed in the tile within a short time after the
supply of formaldehyde and hence, the concentration of the
formaldehyde is decreased.
[0072] However, an absorption strength of the mortar is gradually
decreased along with a laps of time and hence, the concentration of
the formaldehyde is gradually increased.
[0073] Then, as a matter of course, due to the irradiation of
light, in the specimens B to D which contain the photocatalyst,
formaldehyde is decomposed by the photocatalyst and hence, the
concentration of formaldehyde is decreased.
[0074] Further, with respect to the specimen C and specimen D4, it
is possible to decrease the concentration of formaldehyde to 100
ppb or less along with laps of time.
[0075] Particularly, with respect to the specimen D, it is possible
to remarkably decrease the concentration of formaldehyde to
approximately 20 ppb or less.
[0076] Here, to compare the specimen B and specimens C, D which
differ in the lowering of the concentration of formaldehyde after
the irradiation of light, it is understood that these specimens
differ in the pressure at the time of performing the
pressure-forming.
[0077] Accordingly, inventors of the present invention studied in
detail the difference between the specimen B, the specimen C, and
the specimen D. As a result, as shown in FIG. 4 to FIG. 6, it is
found that the specimen B, the specimen C and the specimen D
completely differ from each other with respect to the configuration
of surfaces thereof. These drawings are schematic views for
facilitating the understanding of the present invention and hence,
these drawings do not accurately describe magnification ratios, the
surface structure of the tile or particle sizes of raw materials of
the tile. Since the inspection is made using an electron microscope
in an actual inspection, the inventor is ready for supplying
photographs of these drawings in the examination of the present
invention.
[0078] FIG. 4 is a schematic view showing the vicinity of a surface
of a surface of the specimen B in an enlarged manner. As can be
understood from FIG. 4, when the pressure forming is performed at a
molding temperature of 100 MPa, although some indentations 30 are
found on the surface of the specimen B, the surface is flattened so
that open pores 34 are not found at all. Accordingly, permeability
of the specimen B is impaired and hence, the absorption and the
diffusion of moisture and foreign substances in air are obstructed.
Here, in the drawing, symbol 31 indicates a particle of calcium
hydroxide powder, symbol 32 indicates a particle of porous
aggregate, and symbol 33 indicates a particle of a composite of an
absorption carrier which constitutes a first photocatalyst and
metal compound having a photocatalytic action.
[0079] FIG. 5 is a schematic view showing the vicinity of a surface
of a cross section of the specimen C in an enlarged manner. As can
be understood from FIG. 5, when the pressure forming is performed
at a forming temperature of 30 MPa, open pores 34 are formed on a
surface of the specimen C. The open pores 34 are constituted of
main pores 35 and capillary holes 36. The main poles 35 function as
main tubes which allow the flow of moisture, foreign substances, a
decomposed material or the like and, at the same time, functions as
a light introducing opening for exciting the first photocatalyst
33. Numeral number of capillary holes 36 is formed in a state that
the capillary holes 36 open to the main hole 35 thus allowing the
absorption and the diffusion of moisture in air. That is, the
structure of the fine capillary holes 36 per se takes in and
absorbs moisture in air. Such a phenomenon occurs in numerous open
pores 34 and hence, the permeability is not impaired on the surface
of the specimen C as indicated by a meshed arrow. Further, when the
moisture in air is taken into the capillary holes 36, the foreign
substances in air are also taken into the capillary holes 36.
Accordingly, the foreign substances are decomposed to by the first
photocatalyst 33 exposed in the inside of the main holes 35 and the
capillary holes 36 so as to form decomposed substances. The
decomposed substances are simultaneously diffused with the
diffusion of moisture. In this manner, the specimen C which is
pressure-formed at a forming pressure of 30 MPa can efficiently
absorb and diffuse the moisture in air. Simultaneously, the
specimen C can efficiently absorb, decompose and diffuse the
foreign substances. Based on such a phenomenon, due to extensive
studies made by the inventor, it is found that the manufacture of a
tile which has a practically usable strength can be realized by
performing the pressure forming within a range of 15 to 80 MPa.
[0080] FIG. 6 is a schematic view showing the vicinity of a surface
of a cross section of a specimen D in an enlarged manner. Although
the structure of the specimen D is similar to the above-mentioned
structure of the specimen C, as shown in a right upper portion of
the drawing, the specimen D differs from the specimen C with
respect to a point that a thin layer 37 made of a second
photocatalyst 38 is formed on a surface. However, an enlarged view
which shows the thin layer 37 is a cross-sectional view and the
extension of the thin layer 37 formed on the surface of the
specimen D is not shown in the drawing. However, the thin layer 37
having a film thickness of 50 to 200 nm is substantially uniformly
present on the surface of the specimen D.
[0081] Accordingly, in the same manner as the above-mentioned
specimen C, the moisture and the foreign substances efficiently
flows due to the open holes 34. Further, the thin layer 37 is
formed on a surface of the specimen D and hence, the foreign
substances are efficiently decomposed due to the second
photocatalyst 38. Further, the thin layer 37 has a film thickness
of approximately 50 to 200 nm using the above-mentioned solution
and hence, there is no possibility that the main holes 35 and the
capillary holes 36 are clogged. Accordingly, the flow of the
moisture and the foreign substances is not impeded as much as
possible so that the specimen D can enjoy advantageous effects of
photocatalytic action brought about by the first photocatalyst 33
and the second photocatalyst 38.
[0082] In general, the thin layer made of photocatalyst which is
formed on a surface of an object can exert the influence of the
photocatalytic action only to a material which is in contact with
the thin layer or a material which is away from the thin layer by a
distance of several .mu.m. Further, it is known that fluidity of
air is lowered in the vicinity of a surface of an object such as a
wall due to viscosity of air. Accordingly, only the formation of
the thin layer made of photocatalyst on a surface of an object
exhibits the low fluidity of air on a surface of the thin layer and
hence, the foreign substances cannot be decomposed efficiently.
[0083] On the other hand, in the tile manufactured by a
manufacturing method of tiles according to this embodiment, due to
open pores 34 formed on the surface of the tile, the moisture and
the foreign substances flow efficiently and hence, it is possible
to enhance the fluidity of air along with the efficient flow of the
moisture and the foreign substances. Accordingly, a chance that the
foreign substances in air come into contact with the thin layer 37
is increased leading to the efficient decomposition of the foreign
substances.
[0084] Further, it is known that the photocatalyst requires an
extremely small amount of water to exhibit a photocatalytic action.
However, according to the tile manufactured by the manufacturing
method of tiles according to the present invention, the moisture
can be taken efficiently and hence, it is possible to enhance the
photocatalytic action synergistically.
[0085] As has been explained heretofore, based on the comparison
between the specimen B and the specimen C, by adopting the pressure
which allows the formation of open pores on the surface at the time
of performing the pressure-forming, it is possible to prevent in
advance the situation that the surface of the formed article is
made smooth thus impairing the permeability whereby it is possible
to produce the formed article having the permeability. Accordingly,
it is possible to prevent the decomposition ability of foreign
substances due to the photocatalyst from being lowered.
[0086] Further, based on the comparison between the specimen D and
the specimen 4, it is found that by applying the photoresist to the
surfaces of the tiles, it is possible to obtain the decomposition
ability of contamination substances which is compatible to the
decomposition ability which is obtained when the photocatalyst is
applied to the surface of the tile to which the photoresist is
added. Further, the thin layer made of the second photocatalyst
formed on the surface of the tile using the above-mentioned
solution does not close the open pores and favorably maintains the
permeability.
[0087] Finally, the above-mentioned embodiments are provided only
for an exemplifying purpose, and the present invention is not
limited to the above-mentioned embodiments. Accordingly, it is
needless to say that various modifications can be made
corresponding to designs of tiles or the like without departing
from the gist of the present invention.
* * * * *